Standing Wave Explorer
Drive a string or an air column, sweep the frequency or the length to find resonances, and compare node and antinode patterns for strings, open pipes and closed pipes.
Learning goals
- Describe wave models, use wave quantities and interpret wave graphs in space and time.
- Apply the principle of superposition to resultant displacement.
- Explain standing-wave formation, nodes, antinodes and energy transfer.
- Apply boundary conditions to standing waves on stretched strings.
- Analyse displacement and pressure patterns in resonant air columns and determine sound wavelength.
A string fixed at both ends, 1.000 metres long, driven at 38.00 hertz. It is not resonating, so the reflected waves do not build up.
- Frequency, f
- 38.0 Hz
- Wavelength, λ
- 2.11 m
- Length, L
- 1.000 m
- Wave speed, v
- 80.0 m/s
- Harmonic
- none
Try this
0 of 4 doneMake the string vibrate in three loops. (not done yet)
Three loops is the 3rd harmonic: L = 3λ/2, at three times the fundamental frequency.
Find the lowest resonant frequency of a closed pipe, then of an open pipe of the same length. (not done yet)
The open pipe's fundamental is about twice the closed pipe's: L ≈ λ/2 for an open pipe but L ≈ λ/4 for a closed one.
Find the closed pipe's next resonance above its fundamental. (not done yet)
It is at 3f₁, not 2f₁: a closed end must be a node and an open end an antinode, so only odd harmonics fit.
Keep the frequency fixed and find two successive resonance lengths of the closed pipe. (not done yet)
They differ by half a wavelength, so λ = 2(L₂ − L₁). The end correction cancels in the subtraction.
Your readings
| # | f / Hz | L / m | 1/f / s | Remove |
|---|---|---|---|---|
| No readings yet. Set up a measurement, then record it. | ||||